net/atm: warning in alloc_tx/__might_sleep

From: Andrey Konovalov
Date: Mon Jan 09 2017 - 12:20:45 EST

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Hi!

I've got the following error report while running the syzkaller fuzzer.

On commit a121103c922847ba5010819a3f250f1f7fc84ab8 (4.10-rc3).

A reproducer is attached.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 4114 at kernel/sched/core.c:7737 __might_sleep+0x149/0x1a0
do not call blocking ops when !TASK_RUNNING; state=1 set at
[<ffffffff813fcb22>] prepare_to_wait+0x182/0x530
Modules linked in:
CPU: 0 PID: 4114 Comm: a.out Not tainted 4.10.0-rc3+ #59
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:15
dump_stack+0x292/0x398 lib/dump_stack.c:51
__warn+0x19f/0x1e0 kernel/panic.c:547
warn_slowpath_fmt+0xc5/0x110 kernel/panic.c:562
__might_sleep+0x149/0x1a0 kernel/sched/core.c:7732
slab_pre_alloc_hook mm/slab.h:408
slab_alloc_node mm/slub.c:2634
kmem_cache_alloc_node+0x14a/0x280 mm/slub.c:2744
__alloc_skb+0x10f/0x800 net/core/skbuff.c:219
alloc_skb ./include/linux/skbuff.h:926
alloc_tx net/atm/common.c:75
vcc_sendmsg+0x5e8/0x1010 net/atm/common.c:609
sock_sendmsg_nosec net/socket.c:635
sock_sendmsg+0xca/0x110 net/socket.c:645
___sys_sendmsg+0x9d2/0xae0 net/socket.c:1985
__sys_sendmsg+0x138/0x320 net/socket.c:2019
SYSC_sendmsg net/socket.c:2030
SyS_sendmsg+0x2d/0x50 net/socket.c:2026
entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203
RIP: 0033:0x7fcbacfddb79
RSP: 002b:00007ffed8b5a7b8 EFLAGS: 00000206 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffed8b5a950 RCX: 00007fcbacfddb79
RDX: 000000000000c000 RSI: 0000000020002000 RDI: 0000000000000003
RBP: 0000000000400af0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffed8b5a950 R14: 0000000000000000 R15: 0000000000000000
---[ end trace 9edf2da84d8112da ]---
atm:sigd_send: bad message type 0
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_ioctl
#define __NR_ioctl 16
#endif
#ifndef __NR_sendmsg
#define __NR_sendmsg 46
#endif

#define _GNU_SOURCE

#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/capability.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/sched.h>
#include <net/if_arp.h>

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

const int kFailStatus = 67;
const int kErrorStatus = 68;
const int kRetryStatus = 69;

__attribute__((noreturn)) void doexit(int status)
{
syscall(__NR_exit_group, status);
volatile unsigned i;
for (i = 0;; i++) {
}
}

__attribute__((noreturn)) void fail(const char* msg, ...)
{
int e = errno;
fflush(stdout);
va_list args;
va_start(args, msg);
vfprintf(stderr, msg, args);
va_end(args);
fprintf(stderr, " (errno %d)\n", e);
doexit(e == ENOMEM ? kRetryStatus : kFailStatus);
}

__attribute__((noreturn)) void exitf(const char* msg, ...)
{
int e = errno;
fflush(stdout);
va_list args;
va_start(args, msg);
vfprintf(stderr, msg, args);
va_end(args);
fprintf(stderr, " (errno %d)\n", e);
doexit(kRetryStatus);
}

static int flag_debug;

void debug(const char* msg, ...)
{
if (!flag_debug)
return;
va_list args;
va_start(args, msg);
vfprintf(stdout, msg, args);
va_end(args);
fflush(stdout);
}

__thread int skip_segv;
__thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
_longjmp(segv_env, 1);
doexit(sig);
for (;;) {
}
}

static void install_segv_handler()
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = segv_handler;
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...) \
{ \
__atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \
if (_setjmp(segv_env) == 0) { \
__VA_ARGS__; \
} \
__atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \
}

static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
uintptr_t a2, uintptr_t a3,
uintptr_t a4, uintptr_t a5,
uintptr_t a6, uintptr_t a7,
uintptr_t a8)
{
switch (nr) {
default:
return syscall(nr, a0, a1, a2, a3, a4, a5);
}
}

static void setup_main_process(uint64_t pid, bool enable_tun)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_IGN;
syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
install_segv_handler();

char tmpdir_template[] = "./syzkaller.XXXXXX";
char* tmpdir = mkdtemp(tmpdir_template);
if (!tmpdir)
fail("failed to mkdtemp");
if (chmod(tmpdir, 0777))
fail("failed to chmod");
if (chdir(tmpdir))
fail("failed to chdir");
}

static void loop();

static void sandbox_common()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
setsid();

struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = 128 << 20;
setrlimit(RLIMIT_AS, &rlim);
rlim.rlim_cur = rlim.rlim_max = 1 << 20;
setrlimit(RLIMIT_FSIZE, &rlim);
rlim.rlim_cur = rlim.rlim_max = 1 << 20;
setrlimit(RLIMIT_STACK, &rlim);
rlim.rlim_cur = rlim.rlim_max = 0;
setrlimit(RLIMIT_CORE, &rlim);

unshare(CLONE_NEWNS);
unshare(CLONE_NEWIPC);
unshare(CLONE_IO);
}

static int do_sandbox_none()
{
int pid = fork();
if (pid)
return pid;
sandbox_common();
loop();
doexit(1);
}

long r[11];
void loop()
{
memset(r, -1, sizeof(r));
r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x4000ul, 0x3ul,
0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
r[1] = execute_syscall(__NR_socket, 0x8ul, 0x0ul, 0x0ul, 0, 0, 0, 0,
0, 0);
r[2] = execute_syscall(__NR_ioctl, r[1], 0x61f0ul, 0x20003000ul, 0, 0,
0, 0, 0, 0);
NONFAILING(*(uint64_t*)0x20002000 = (uint64_t)0x0);
NONFAILING(*(uint32_t*)0x20002008 = (uint32_t)0x0);
NONFAILING(*(uint64_t*)0x20002010 = (uint64_t)0x20002000);
NONFAILING(*(uint64_t*)0x20002018 = (uint64_t)0x2);
NONFAILING(*(uint64_t*)0x20002020 = (uint64_t)0x0);
NONFAILING(*(uint64_t*)0x20002028 = (uint64_t)0x0);
NONFAILING(*(uint32_t*)0x20002030 = (uint32_t)0x0);
r[10] = execute_syscall(__NR_sendmsg, r[1], 0x20002000ul, 0xc000ul, 0,
0, 0, 0, 0, 0);
}
int main()
{
setup_main_process(0, false);
int pid = do_sandbox_none();
int status = 0;
while (waitpid(pid, &status, __WALL) != pid) {
}
return 0;
}

Next message: Eric Dumazet: "Re: net/ipv6: use-after-free in sock_wfree"
Previous message: Stephen Hemminger: "Re: [PATCH 3/4] hv_util: use do_adjtimex() to update system time"
Next in thread: Cong Wang: "Re: net/atm: warning in alloc_tx/__might_sleep"
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